Good day

For one week now, since last Sunday, our Vestwood Lithium Battery 51.2 V 100Ah 5.12kW – VW-BAT-LITH-VT48100E battery gets to 100% in the day but from 6 pm when there is no solar discharges at a rate of 31 to 33% and hour. I noted after two days that there was suddenly an added demand on Eskom to support the house at night. 18.3kWh used over the last 6 day mostly when we are asleep averaging 3.66kWh per night. I did call the installer on Tuesday past and he responded on Thursday to advise they had looked at the data and the problem does not appear to be the battery. It appears to be the invertor and the BMS - I assume Battery Management System. He would need to upgrade the invertor, Luxpower SNA5000 WPV 5KW 48V, firmware. He will doe this tomorrow and then we would know.

As you are aware we are now in Stage 6 and last night I woke just before 2am and initiated a quick charge. The battery go to 79% before Eskom bailed, This morning at 5am this had run down to 17%. I also note that the consumption load at that time was 204W, which I assume as we were sleeping was a constant for those past 3 hours, Now I am not a mathematician but was wondering if anyone could assist with telling me if using 204W over 3 hours what %age of a 5kVa battery should be discharged (used). Trying to figure what points I can set the auto recharge request from Eskom without dropping too low, say below 25% again.

We are trusting that the firmware upgrade works. The first this said to me was you should by a second battery to increase storage. I said NO, the battery is clearly not storring. 

Installation - battery and invertor was done in June 2023. In December 2023 battery was doing the same - discharging and then they monitored, tokk battery away and did test and got supplier to monitor and agreed the battery was faulty. No cause given for why suddenly faulty. No changes were done to Invertor. We are worried that we now hear it is an invertor firmware issue.

Thanks

 

Not a reply but to add - my wife just asked me if the systems need upgrades, how are we informed of the same? We do not see it on the laptop dispaly.

1 hour ago, GregM1 said:

As you are aware we are now in Stage 6 and last night I woke just before 2am and initiated a quick charge. The battery go to 79% before Eskom bailed, This morning at 5am this had run down to 17%. I also note that the consumption load at that time was 204W, which I assume as we were sleeping was a constant for those past 3 hours,

Not a safe assumption. Do you not have access to some tool that gives you a graph like this one from my system? 

They are not all exactly like this, but something similar. You can see it tracing load (yellow line), power in or out of battery (purple) and battery's state of charge (green).

The left of the graph is midnight. The house is running off of the battery. A quick check shows a low of 110W, a high of about 350. This is the house ticking over at night. WIFI, outside lights, fridges, stuff on stand by, security system. 

Anyway, my point is that the load is not constant at night. Mine doesn't fluctuate a lot, but it is not constant.
 

1 hour ago, GregM1 said:

Now I am not a mathematician but was wondering if anyone could assist with telling me if using 204W over 3 hours what %age of a 5kVa battery should be discharged (used). Trying to figure what points I can set the auto recharge request from Eskom without dropping too low, say below 25% again.

OK... your battery has a capacity of 5.12 kWh (per the link you shared). 204 W per hour (assuming that is the average load) gives 1.02 kWh in 5 hours. So you should be losing about 20% every 5 hours - simple arithmetic. 4% an hour IF the average load is 204W, but we can't be sure of that. I lost about 7% over 4 hours, but my battery is double yours. So I can back calculate to an average of 175W.

Now your tale above shows a 62% lost over... it's not clear what period of time. We know that the battery was at 79% when charging stopped because the grid went down. But even if we assume 79% at 02:00 then you were discharging at 20% an HOUR (02:00 to 05:00) to get to 17% by 5:00, five times the rate if the average was 204W.

So something has to give. Either you are using a lot more than you know/expect at night, or some part of your system is not in good shape.

NB! The inverter itself will account for some of the load. Converting 50V DC to 230V AC is not a 100% efficient matter, and also the inverter is going to use some electricity just to keep itself up and running.

So we need to understand what the loads truly are. Either you can work a night shift monitoring the system and capturing numbers into a spreadsheet, or you need a tool like the one I show. Between you and the installer, one of you should have access to that data. Check that. If you see much higher loads than you expected then you can investigate.

Get that data. See what loads are active during the night, then you can make better judgements and decisions.

Ask the installer how possible it is that the geyser is getting power from the battery.
 

Edited February 11, 20242 yr by Bobster.

Thanks for feedback Bobster - Do have such graphic and note the fluctuation. Will try to work out an average over 6 hours.

Anyone know how to update firmware on vestwoods 5kva batt and where to download it?